The most popular pie is the Julian, topped with kale, Calabrese sausage, onion, garlic, and chili flakes. Owners Karen and Will Gioia named it after their son.

Signature dishes don’t just become signature dishes all by themselves. A chef or restaurateur might serve some personal favorite, classic, and/or ambitious dish, but only customers can turn it into a trademark.

The most popular pie at Berkeley’s 15-year-old Gioia Pizzeria is the Julian, topped with kale, Calabrese sausage, onion, garlic, and chili flakes.

Owners Karen and Will Gioia — who met during their first day as students at the Culinary Institute of America in Hyde Park, N.Y. — named it after their son.

Now 11, “Julian grew up in the shop, so it only seemed right to name a pizza after him, as we are completely smitten with him,” Karen Gioia said, warning that this pizza tends to shift — not with the seasons, as do most of the pair’s other pies, but with their son’s states of mind.

“The Julian changes with his mood and temperament,” Gioia explained.

When he’s being “sweet and curious,” the toppings expand to include butternut squash, gorgonzola cheese, and caramelized red onion. When he’s being “a straight-up goofball,” the Julian becomes more “ham-and-cheesy.”

“We feel that the balance of salt, sweet, spicy, and fat is always important in any dish we make,” Gioia said.

House-making their own Calabrese sausage — an homage to Will Gioia’s ancestral roots in Italy’s Calabria region — the couple sources ingredients from semi-local farms such as Dirty Girl, Star Route, and Riverdog, as well as from San Francisco’s Japanese Pantry. They collaborated with Oakland’s Oaktown Spice Shop to create a new spice blend that customers can shake over their purchases.

After operating a full-service San Francisco restaurant for six years, then closing it last fall, the Gioias launched a new San Francisco fast-casual location this June.

On the menu at Hayes Valley’s first-ever slice shop are salads, East Coast-ish hero sandwiches, and the couple’s renowned pizzas — including, of course, the Julian.

This signature dish in its classic form is topped with hot peppers because a variety of these grows abundantly in Calabria — “so, as a family, we love chilis,” Gioia said.

“And, oftentimes, Julian” — the pizza and the boy — “is spicy.”

Gioia Pizzeria, 1586 Hopkins St., Berkeley, 510-528-4692, GioiaPizzeria.com.